The studies in this proposal are designed to investigate the effect that Alzheimer's disease has upon the structure and accessibility of semantic memory. The tasks used will be similar to those which have shown semantic memory to remain relatively intact in the normal elderly. Here, we will determine whether semantic memory is also spared in demented patients who show severe episodic memory decrements. Patients with mild to moderate dementia of the Alzheimer's type will be compared to age matched normal subjects on a semantic priming task, as well as on two tasks which examine the degree to which they can use their knowledge of English orthography to facilitate visual search and short term memory. These studies will help characterize the nature of the memory deficits found in Alzheimer's disease, especially with respect to memory processes which appear to be relatively resistent to the changes seen in normal aging.